1. Field of the Invention
The present invention relates to an ink jet printer head and an ink jet printer for printing with a mixed liquid in which a transparent solvent and an ink is quantified and mixed.
2. Description of the Related Art
For example, with respect to on-demand ink jet printer, ink is discharged by using pressure caused by the distortion of an electrostrictive element (a piezoelectric element or a piezo element) and pressure of bubble generated by heating and boiling by a heating element.
In the on-demand ink jet printer, gradation is represented by one kind of ink. More specifically, in an ink jet printer which can discharge only one kind of liquid (ink), gradation representation by one dot is performed by area gradation that the size of one dot of ink sticking to the material to be printed is controlled by controlling the amount of ink discharged at one time.
However, since it is extremely difficult to perform fine control of ink discharged at one time, there have been problems as rich gradation printing cannot be obtained, representation capabilities are poor in the highlighted portion, and so on.
Therefore, an ink jet printer has been developed which performs printing by discharging a mixed liquid of a transparent solvent and ink.
In such an ink jet printer, printing is performed using in-dot density gradation in which either the transparent solvent or the ink, e.g., ink, is quantified in accordance with a desired gradation representation, and mixed with the predetermined transparent solvent as the other liquid, and determined the definite mixed liquid amount to perform discharge printing.
The applicant of the present invention has already disclosed an ink jet printer which makes use of, for example, electrical permeation to quantify ink (or transparent solvent), as an ink jet printer using a mixed liquid mixing two (or more) liquids as described above, in U.S. patent application Ser. No. 07/961,982 which is in pending.
Here, electrical permeation is referred to as a phenomenon in which a vessel filled with the electrolyte solution is provided with a porous barrier membrane to partition the chamber into two, and an electrode plate is inserted into left and right electrolyte solutions so that, when a voltage is applied, the electrolyte solution moves from one chamber to another via the porous barrier membrane.
Electrical permeation allows relatively accurate quantification because the permeation amount (movement amount) of the electrolyte solution stands in proportion to the amount of flowed electricity.
However the frequency response of electrical permeation phenomenon, is slow compared with, for example, a piezoelectric element, thereby making it difficult to increase the printing speed.
Moreover, ink and transparent solution are mixed in transparent solution, so that they come to be mixed spontaneously.